1. Field of the Invention
The present invention relates to a marine bacterium, Alteromonas sp. SN2 (KCTC11700BP) having an activity for degrading polycyclic aromatic hydrocarbon (PAH), a bioremediation process of PAH contaminants using the same, and a composition for purifying PAH contaminants using the same.
2. Description of the Related Art
Naphthalene flowed into wastewater during bioremediation processes of petroleum or coke because it was highly contained in oil or coal tar. Likewise, wastewater containing naphthalene may be a crucial factor causing difficulty in manipulation of wastewater treatment system, for example including inhibition of microorganism growth and delay of reaction time during activated sludge processes. Conventionally, solvent extraction method has been utilized in removal of naphthalene contained in the wastewater. However, solvent extraction method has severe drawbacks such as low economic efficiency and complicated processes in the senses that chemicals of organic components involved in wastewater are extracted with solvent, followed by combustion or incineration of extracted solvents.
According to the principles of treatment technologies, bioremediation process of contaminated soil is divided into: (a) thermal technology degrading toxic materials by incineration or thermal-decomposition through exposing soil to higher temperature; (b) stabilization and solidification technology preventing contaminant transport by formation of solid materials; (c) soil vapor extraction technology extracting and treating polluted air through pore of contaminated soil; (d) physical and chemical extraction technology in which a heavy metal is treated with water, acid, organic solvent, etc.; and (e) microbial treatment technology promoting biodegradation of organic chemicals by activating soil bacteria.
The treatment process such as thermal technology, solidification technology and vapor extraction technology has the following problems: (a) secondary contaminations such as incomplete incineration or residual solvents, and environmental disturbance, and (b) higher treatment cost.
Meanwhile, bioremediation is a process in which a toxic material is converted into a material having low toxicity using a microorganism or its metabolite. This technology utilizes a process in which contaminants are converted into non-toxic carbon dioxide by microorganism using them as carbon and energy source. This technology is based on carbon cycle, and carried out whereby carbon is repeatedly cycled through redox reactions between inorganic and organic material (Roling, W. F. M. et al. The microbiology of hydrocarbon degradation in subsurface petroleum reservoirs: Perspectives and prospects. Res. Microbiol. 154: 321-328 (2003)).
In this context, economics and efficiency of bioremediation have been already demonstrated in numerous case studies and practical application studies in the senses that bioremediation not only allows much more lower secondary contaminations, but also most economical processes up to now due to natural attenuation's ability (Margesin R, Schinner F. Bioremediation (Natural Attenuation and Biostimulation) of Diesel Oil Contaminated Soil in an Alpine Glacier Skiing Area. Applied and Environmental Microbiology 67: 3127 (2001)).
As supply source of microbes, there are the following methods: (a) bio-stimulation method using indigenous microorganisms propagating in a contaminated region; and (b) bio-augmentation method supplying foreign microorganisms having an activity for degrading a specific contaminant, which are massively cultured in the laboratory. Particularly, the latter method has shortcomings such as: (a) high probability that foreign microorganism injected fails to be predominant species due to defeat in survival competence with indigenous microorganisms; and (b) high possibility that unexpected environmental disturbance is caused by metabolites of foreign microorganism.
Example of the former method is as follows: (a) a method for removing contaminants by growing and proliferating indigenous microorganism without injection of foreign microbe to a polluted region; and (b) a method that indigenous microorganism isolated are massively cultured in the laboratory and re-injected into a contaminated region. The former has a demerit that total restoration period in a polluted region is prolonged for a long time as lag time is excessively required in an early restoration period until indigenous microorganisms reach at above certain individual number.
Therefore, the methods to utilize microorganisms cultured massively in the laboratory have been applied to overcome defects as described above, and there has been urgently demanded the necessity of novel microbial strains and processes for biologically purifying soil, fresh water or seawater contaminated with any type of oil (particularly, naphthalene).
Throughout this application, various patents and publications are referenced and citations are provided in parentheses. The disclosure of these patents and publications in their entities are hereby incorporated by references into this application in order to more fully describe this invention and the state of the art to which this invention pertains.